Draw-in chuck



J. N. HEALD AND A. M. DRAKE.

DRAW-IN CHUCK.

APPLICATION F|LD1uNE14,192o.

ITS z5 2F Patented Apr. 18, 1922.

UNITED STATES PATENT OFFICE.

JAMES N. HEALD AND ALBEN M. BRAKE, OF WORCESTER, MASSACHUSETTS,

ASSIGNORS TO HEALD MACHINE COMPANY, 0F WORCESTER, MASSACHU- SETTS, A CORPORATION OF MASSACHUSETTS.

DRAW-IN CHUCK.

To all whom t may concern.'

Be it known that we, JAMES N. HEALD and ALDEN M. DRAKE, both citizens of the United States, and both residing at Worcester, m the county of Worcester and State of Massachusetts, have invented a new and use-ful Draw-In Chuck, of which the following is a specification.

This invention relates to a draw-in chuck and particularly to certain improvements by which such chucks are better adapted for holding work which is easily distorted.

It is the general object of our invention to provide a draw-in chuck by which the pressure of the jaws upon the work may be controlled and limited, and in the preferred form may be adjusted as desired.

With this general object in view, one embodiment of our invention provides a yielding connection to the draw bar by which only a pre-determined pressure may be transmitted to the work.

Our invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claims.

A preferred form of our invention is shown in the drawings, in which Fig. 1 is a longitudinal view of a chuck embodying our invention;

Fig. 2 1s a transverse sectional elevation taken along the line 2-2 in Fig. 1; and

Fig. 3 is a side elevation of the spring plate.

or disc.

Referring to the drawings, we have shown a spindle 10 supporting a head 11 having a conical recess 12 at the outer end thereof. We have also shown a work-holding member 13 comprising a plurality of spring jaws 14 and having a conical outer surface fitting the conical recess 12. A draw bar 15 is secured to the member 13 and extends rearward through the spindle 10. A grooved collar 16 is mounted to slide on the outside of the spindle 10 and may be moved axially by a yoke 17 on a hand lever 18. j

The draw bar 15 is threaded at its rear end to receive an adjusting nut 20 and lock nut 21. The rear end of the spindle 10 is also threaded tb receive a collar 22 having slotted lugs or projections 23 in which levers 24 are pivoted.

All of the parts thus far described may be Specification of Letters Patent.

Patented Apr. 18, 1922.

- Application led June 14, 1920. Serial No.'388,739.

of any usual construction and form no part of our invention.

A spring plate or disc 25 is positioned on the draw bar 15 by the nuts 20 and 21 and is engaged by the cam-shaped rear ends of the levers 24. The oppositeends of the levers contact with the conical end 26 of the grooved collar 16. When the collar 16 is moved rearward or to the left in Fig. 1 to tighten the chuck, the levers 24 are swung on their pivots and transmit pressure through the disc 25 to the nut 20 and draw bar 15. As the pressure is wholly transmitted through the spring plate, it cannot exceed the pressure which will cause the plate to bend or buckle.

It is thus impossible for the workman to place excessive strain upon the work by aplying increased pressure to the lever 18.

he amount of pressure to be transmitted may be regulated by adjusting the nuts 20 and 2l, it being evident that the pressure maybe reduced by slight additional separation of the disc 25 and levers 24.

This form of chuck is found particularly serviceable in internal grinding machines, wheremuch of the work is of limited thickness or is of such construction that it is easily distorted.

Having thus described our invention, it will be evident that changes and modifications can be made therein by those skilled in the art within the spirit and scope thereof as set forth in the claims and we do not wish to be otherwise limited to the details herein disclosed, but what we claim is 1. A draw-in chuck comprising a casing, a work-holding member fitting within said casing, a draw bar, for said member and manual means to draw sai-d member into said casing to grip the work, said means including a spring disc mounted on said draw bar and engaged near its outer edge by other parts of said manual means mounted in bearings xed on said casing.

2. A draw-in chuck comprising a casing, a

work-holding member fitting within saidl casing, a draw bar for said member, and manual means to draw said member into said casing to grip the work, said means including a spring disc mounted on said draw bar anden aged near its outer endge by other parts o said manual means mounted in bearings fixed on said casing, and devices for adjusting said disc on said draw bar..

3. A draw-in chuck comprising a casing, a Work-holding member fitting within said casing, a draw bar for said member, and means to apply yielding pressure to said bar to draw said member into said casing to grip the Work, said means including a pair of levers pivoted at points fixed in relation to v10 said casing, a sleeve slidably mounted and 

